The research will seek some of the effects of antibody on plaque formation and determine the presence of immunoglobulins in human dental plaque. The research plan has two major directions: (1) In rats, a study of the effects of specifically induced secretory IgA antibody on experimental periodontal disease caused by Actinomyces naeslundii or Streptococcus mutans. (2) In humans, an investigation of the immunoglobulins in plaque and studies of the immune response in parotid and minor salivary gland secretions and studies of the effects of "natural" secretory IgA antibody on binding of bacteria to hydroxyapatite in vitro. A combination of immunological and biochemical techniques will be employed in these investigations. Gnotobiotic rats will be utilized for specific immunization studies. In particular, radiolabelled antiserums will be used to study salivary response and fluorescent antibody technique to study tissue response. Human studies will involve in vitro binding of bacteria and "natural" secretory IgA antibody effects on this binding and the technique of bacteriophage neutralization to detect antibody in secretions.